Iron compounds from vegetable origin that mimic iron from animal
sources may enhance the bioavailability of the mineral and boost
fortification programmes, says a new study from Unilever.

Sodium iron chlorophyllin obtained from mulberries was found
to be as bioavailable as heme iron, scientists from Unilever R&D
Vlaardingen in the Netherlands report in the Journal of Agricultural
and Food Chemistry.

Understanding the challenge

Iron deficiency remains the leading nutrient deficiency in both
developed as well as developing countries. It affects around one
in five women in the UK.

Fortifying foods with iron also poses several challenges for
the food industry, most notably with regards to effects on colour,
taste, and the shelf-life of the food.

Iron fortification of foods generally has used non-heme
iron sources, as these are cheap and easily available, explained
the researchers, led by Silvia Miret. Nevertheless, these
iron sources have poor bioavailability and often affect the organoleptic
characteristics of the product.

The use of heme-iron as a fortificant has been limited,
they continued. This probably responds to a myriad of factors
including the elevated costs of haemoglobin or haemoglobin extracts,
the intense colour of haemoglobin, the large amounts of haemoglobin
required, and its animal origin, which means that it might not
be consumed in certain regions of the world.

In order to address this issue, the researchers looked at iron
compounds from vegetable origins which are analogues of heme-iron.
They focussed their attention on sodium iron chlorophyllin, a
compound described by the researchers as a water-soluble
semi-synthetic chlorophyll derivative where the magnesium in the
porphyrin ring has been substituted by iron.

By using Caco-2 cells to model bioavailability in the human intestine,
the researchers found that sodium iron chlorophyllin was stable
under simulated gastrointestinal conditions and is able to deliver
bioavailable iron.

Various food matrices were considered, including water, dough,
powder drink, and chocolate. Iron sulphate was used as a comparison.
Miret and her co-workers report that, as with heme-iron, the bioavailability
of the iron from sodium iron chlorophyllin was dependent on the
food matrix. Indeed, calcium was found to inhibit the bioavailability.

Choose your matrix carefully

It should be noted that sodium iron chlorophyllin is intensely
green, and therefore, it dramatically affects the colour of the
food matrixes where it is added, wrote the researchers.
Coloration could be masked in the presence of cocoa both
in chocolate bar formats as well as in drink products.

Miret and her co-workers note that the fruit drinks containing
strawberry have been found to effectively mask the colour of the
compound, suggesting an alternative delivery method for the compound.

Nevertheless, it is clear that for this compound colour
is a major factor and that strategies should be considered for
masking or linking it to particular green flavours such as pistachio
or kiwi, they added.

Promising beginnings

Potentially, sodium iron chlorophyllin could be used as
an iron fortificant from vegetable origin with high bioavailability
similar to that of heme, wrote the researchers.

Adequate product formulation and in particular the absence
of calcium would be essential to ensure iron delivery. These iron
bioavailability results should be corroborated in human intervention
studies, they concluded.